There are many industrial and automotive applications in which an integrated circuit (IC) switch is used to control current supplied to external components such as solenoids, relays, and motors; and such IC switches may be included as part of a current regulator, switched mode power supply, or a synchronous rectifier. Electronic-controlled transmissions and antilock brakes often employ such IC switches, as do switched power supplies employing Buck or Flyback architectures operating in discontinuous conduction mode (DCM).
In these and other applications, the IC switches may be called upon to support bidirectional current flow in a controlled manner. When only unidirectional flow is anticipated, there exists an elegant “sense transistor” technique for monitoring the current density through the switch. However, for reverse current flows through metal-oxide-semiconductor field-effect transistors (MOSFETs) the sense-transistor technique becomes inaccurate. An approach based on existing techniques would require the use of current monitoring circuitry that adds undesirable complexity and cost to the IC switches.